1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method, particularly to an image forming apparatus and an image forming method used for rendering.
2. Description of the Related Art
In recent years, a shift from monochrome print to color print has been progressing in image processing apparatuses (image forming apparatuses) represented by a digital multifunction peripheral (MFP). The shift to color print causes an increase in the amount of information processed in the image processing apparatuses. Also, demand for higher printing speed has been increasing, and a faster process in the image processing apparatuses has been demanded. Under such circumstances, the following method for increasing the speed of a process in a print job input from a host computer to an image processing apparatus is generally known.
In a typical system to generate raster image data by interpreting input page description language (PDL) data, an intermediate language in the form of a display list (DL) is generated by interpreting the PDL data. The DL as intermediate language is then converted to a raster image. The process of converting the intermediate language to a raster image is known as rendering. In the series of processes, a very heavy load is imposed on the process in rendering, but the rendering can be realized by hardware relatively easily. Therefore, rendering-dedicated hardware (hard renderer) is mounted on the system to increase the speed of rendering in typical cases.
However, in the rendering-dedicated hardware, the size of various tables used in works during rendering is limited due to a hardware property. For this reason, the rendering-dedicated hardware is not capable of rasterizing complicated data at a time. In view of this, there is a technique of simultaneously performing rendering by hardware and rendering by software on PDL data that is not rasterized at a time and using a result of the earliest completed rendering (see Japanese Patent Laid-Open No. 2004-66532).
In an image processing apparatus, such as a digital MFP, a copy job or the like may be required to be performed with higher priority than a print job. Thus, if a copy job is input to the image processing apparatus while a print job is being processed (in particular while a hardware renderer is rendering PDL data input thereto), the copy job should be preferentially executed by suspending the hardware renderer. In the related art, however, such a method causes suspension of rendering of PDL data and delay in completing rendering.